1. Field of the Invention
The invention relates to the thermal treatment of material.
2. Description of the Prior Art
Calcination is a form of thermal treatment in which a material undergoes a chemical change. Particulate material is typically calcined by entraining the material in a gaseous medium and heating the material. This procedure, known as flash calcination, is carried out in different ways depending on the specific calcining characteristics of the material being calcined.
Almost all flash calcining methods involve the three operations of preconditioning, calcining and cooling. Preconditioning may include the steps of reducing particle size, screening and drying, and the purpose of preconditioning is to produce a uniform, free-flowing substance for the calcining operation. Calcining can be performed utilizing equipment of various designs and, following calcination, the calcined product is separated from the gaseous medium in which calcination took place. The calcined product is then cooled and deposited in a storage vessel.
A calcining method and plant are disclosed, for example, in U.S. Pat. No. 5,975,892.